1. Field of the Invention
The present invention relates to an organic copolymer having an inorganic functional group and an organic-inorganic hybrid polymeric material prepared from the copolymer.
2. Prior Art
Plastics is superior in molding processability, productivity, light weight, flexibility, mechanical properties and electrical properties, which can substitute for existing materials such as metal, glass, wood and paper, so as to be used for manifold fields such as construction materials, structural parts and mechanical parts of electric and electronic products, exterior and interior parts of automobiles, vehicles, aircraft and ships, daily miscellaneous goods and packing materials. For this reason, there are many kinds of plastics.
With regard to the classification of plastics, they are first roughly divided into thermosetting resin and thermoplastic resin. Thermosetting resin is a resin which causes crosslinking reaction by heating a prepolymer so as to cure. Accordingly, thermosetting resin has flowability before curing and does not soften nor melt even by reheating once after curing. An example thereof involves phenolic resin, urea resin, melamine resin, unsaturated polyester, diallyl phthalate resin, epoxy resin, polyurethane, silicone resin, alkyd resin, and the like.
On the contrary, thermoplastic resin is a resin which melts by heating and solidifies by cooling. Thermoplastic resin softens and melts by reheating even after curing once, thereby being appropriately used for molding. For that reason, thermoplastic resin has been recently occupying approximately 90% of total production of plastics. This thermoplastic resin can be classified into general-purpose plastics and engineering plastics.
An example of general-purpose plastics involves polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyvinyl alcohol, polyvinyl acetal, polyethylene, polypropylene, polystyrene, AS resin, ABS resin, polymethyl methacrylate, polyacrylic acid, polyacrylonitrile, polybutadiene, polyethylene terephthalate, and the like; most of them are a polyethylene-based polymer. These are currently most-used plastics in view of inexpensiveness. As compared with engineering plastics, however, these are inferior in the aspect of physical properties such as heat resistance and mechanical properties, thereby not being appropriately used for industries and structural materials.
Engineering plastics have been developed as substitute materials for metallic materials for the purpose such as lightening, downsizing, highly performing and cost-reducing, being mainly used for industries. Physical properties of engineering plastics are generally superior to the above-mentioned general-purpose plastics. Polycarbonate, polyamide (nylon), polyacetal, polybutylene terephthalate, modified polyphenylene ether, glass-fiber reinforced polyethylene terephthalate, and the like are much in demand and denominated general-purpose engineering plastics.
Also, among them, engineering plastics developed so as to have further superior physical properties are denominated as super engineering plastics. An example of super engineering plastics involves polyarylate, polysulfone, polyether ether ketone, polyimide, polyamide imide, fluororesin, liquid crystal polymer, and the like. Most of these engineering plastics are condensation polymers.
Currently, the improvement of various properties of plastics and costs thereof have been increasingly required by the market. It is, however, difficult to develop new plastics meeting these requirements one after another, so that the improvement of the properties of plastics has been actively attempted by combining different kinds thereof.
For example, copolymerization is a method of synthesizing a polymer by combining plural monomers of different kinds. Most of the above-mentioned plastics are homopolymers composed of one kind of structural unit, while plural structural units can be introduced into one molecule of a polymer by copolymerizing. Some combinations of monomers can cause different properties from homopolymers composed of each of single the monomers so as to realize high performance. Also, variation of a polymerizing method can make a random polymer, a block polymer and a graft polymer to be highly functionalized. AS resin and ABS resin of general-purpose plastics are examples thereof and copolymers composed of acrylonitrile/styrene and acrylonitrile/butadiene/styrene respectively.
Thus, in the case where each segment as a component of a copolymer is synthesized by the same polymerizing method, the difficulty is somewhat different in accordance with an intended form (random, block and graft); nevertheless, the synthesis of a copolymer is not so difficult. However, in the case of combining segments polymerized by a different method, the synthesis of a copolymer is difficult, and thereby consideration is required for a synthesizing method.
For example, a method of combining a polyethylene segment and a polycondensation segment by synthesizing is described in Japanese Patent Laid-open Publication No. S59(1984)-27908, Japanese Patent Laid-open Publication No. S61(1986)-19630, Japanese Patent Laid-open Publication No. H9(1997)-302196, and the like. Here, such a copolymer is synthesized by using a macropolymerization initiator having a polycondensation segment and a polymerization initiating part in a molecule.
On the other hand, introduction of an inorganic component such as Si, Ti and Zr into a backbone of an organic polymer has been attempted in order to further improve the properties of plastics such as surface hardness, luster, antifouling property, strength, heat resistance, weather resistance and chemical resistance. In particular, organic-inorganic hybrid polymeric materials such that an inorganic component is dispersed into an organic component at a molecular level have high performance and high function, thereby being promising as a new raw material.
In Japanese Patent Laid-open Publication No. H8(1996)-104710 and Japanese Patent Laid-open Publication No. H8(1996)-104711, a method of radical-polymerizing an ethylenically unsaturated monomer (hereinafter referred to as merely ‘an unsaturated monomer’) by using an alkoxysilyl group-terminated azo-based initiator so as to hydrolyze and condense the obtained alkoxysilyl group-terminated polyethylene polymer is described as a preparing method of organic-inorganic hybrid polymeric materials. However, the obtained organic-inorganic hybrid polymeric materials have an organic backbone of a polyethylene structure and are low in heat resistance and mechanical strength, thereby not being appropriately used for industries and structural materials.
A method of introducing an alkoxysilyl group by utilizing a terminal hydroxyl group of polybutadiene so as to subsequently hydrolyze and polycondense this, is described as another preparing method of organic-inorganic hybrid polymeric materials on page 973 of Polymer Vol. 39, No. 4, published in 1998 and page 965 of Polymer Vol. 39, No. 4, published in 1998. Also, a method of introducing an alkoxysilyl group by utilizing a terminal hydroxyl group of polycaprolactone so as to subsequently hydrolyze and polycondense this, is described on page 855 of Polymer Vol. 39, No. 4, published in 1998 and page 3983 of Polymer Vol. 37, No. 17, published in 1996. Also, a method of introducing an alkoxysilyl group into a terminal of polyphenylene terephthalamide so as to hydrolyze and polycondense this, is described on page 4523 of Polymer Vol. 38, No. 17, published in 1997. Also, a method of introducing an alkoxysilyl group into polyether having an allyl group at a terminal by utilizing a hydrosilylation reaction is described in Japanese Patent Laid-open Publication No. H5(1993)-43679.
Most of engineering plastics are condensation polymers synthesized by a polycondensation reaction. Polymerization in a polycondensation reaction is performed by reacting a condensable functional group in monomers, and the functional groups are mostly consumed except for a molecular terminal, after the polymerization reaction. Accordingly, an alkoxysilyl group-containing polymer obtained by these conventional methods is of a type such that one alkoxysilyl group exists at both terminals of an organic polymer.
That is to say, in a conventional alkoxysilyl group-containing polymer, the number of alkoxysilyl groups contained in the polymer is restricted to two groups with respect to one molecule. Therefore, organic-inorganic hybrid polymeric materials obtained by hydrolyzing and polycondensing these polymers have a small quantity of inorganic components and crosslinking points, and the properties of plastic materials such as strength, heat resistance, weather resistance and chemical resistance are not sufficiently improved.